1. Field of the Invention
The present invention concerns a finely divided silicone rubber additive material and a method for manufacturing this material. In particular, this invention concerns a finely divided cured silicone rubber which is particularly suited for use as a reinforcing agent for a variety of materials, including elastomers and resins.
2. Description of the Prior Art
In recent years, finely divided silicone rubber particles have been used as additives for organic resins to impart or improve properties such as, for example, water resistance, shock tolerance, strength, and as internal stress-relaxation agents for hard and brittle organic resins.
Finely divided silicone rubber particles and methods of manufacture these materials are known in the art. These methods include, for example, spraying a liquid silicone rubber composition into a high-temperature gas where the composition hardened in spray form to yield a silicone rubber particulate having spherical particles with excellent lubricating properties. This method is disclosed in Japanese Patent Publication 59/68,333.
Japanese patent publication No. 61/101,519 teaches heat treating a mixture of a high molecular weight, powdered dimethylsiloxane and a silane substituted with an epoxy group for the purpose of preparing a dimethylpolysiloxane powder having a surface covered with the silane. This powder is not a rubber and therefore does not exhibit the typical properties of a rubber in that it is readily deformed when subjected to external stresses and is readily soluble in various solvents. These properties make handling of the material difficult. Because the material lacks rubbery elasticity it is not very effective in absorbing impact energy and relaxing stress. These properties limit applications for the material, and makes it less than entirely satisfactory.
The present inventors conducted a number of investigations aimed at resolving the foregoing problems of compatibility and adhesion. These investigations resulted in the products and method described in this specification.
One objective of this invention is to provide a novel type of finely divided silicone rubber which is particularly suitable for use as a reinforcing agent for various organic resins and rubbers. A second objective is to provide a method for manufacturing this finely divided silicone rubber particulate.